Changing database in Phreeplot

[jt2020]

Hello there,

I am trying to produce phase diagrams in Phreeplot and need to change database from wateq4f.dat to minteq.dat. After that, ill have to try producing phase diagrams at different temperatures and pressures (but one step at a time).

I have added minteq.dat to the input file but when running it, it says that the main species, Fe, could not be found. Odd, as it is in the Minteq database which is very similar to wateq4f.dat. I have copied my input below.

SPECIATION
  JobTitle                             "Test"
  database                             MINTEQ.DAT
  calculationType                      ht1       # hunt & track method - could also use 'grid' approach
  calculationMethod                    1
  mainSpecies                          Fe
  resolution                           200
  xmin                                 2.0       # this determines the scope of the x-axis variable
  xmax                                 12.0      # ibid
  ymin                                 -85.0     # this determines the scope of the y-axis variable
  ymax                                 0.0       # ibid
  pdf                                  T         # file conversions using Ghostscript
  png                                  T
  jpg                                  T
  eps                                  T

PLOT
  plotTitle                            "Fe-O₂-H₂O"
  xtitle                               "pH"
  ytitle                               "Eh (V)"
  yscale                               Eh        # this makes the y-axis 'Eh' rather than log f O2(g)
  text                                 auto 10.5 1.1 "<mainspecies>" 5 blue 0 1:\
                                       auto 2.5 -0.8 "0.1 mol/kgw NaCl25^oC" 2 black 0 0
# nudge measures shift in labels in terms of the units of distance in force - here assumes the default, i.e. mm
# nudge plotnumber labelnumber label diff/abs x y [angle pos]
  nudge                                1 auto "O2(g) > 0.21 atm" diff 0 0 : 1 auto "H2(g) > 1 atm" diff 0 -1.5

CHEMISTRY

include 'ht1.inc'                      # this pulls in the special hunt and track code from the system directory

SOLUTION 1
   pH        1.8                       # starting with a low pH ensures that the entire pH range from 2-12
   units     mol/kgw                  # can be reached by titration with NaOH
   Fe(2)     1e-6
   S(-2)     1e-4
   HCO3-     1e-2
   Na        1e-1
   Cl        1e-1
SAVE solution 1
END

# second simulation - by default, loops on the last simulation only
USE solution 1
EQUILIBRIUM_PHASES 1
   Fix_H+ -<x_axis> NaOH 10
     -force_equality true
   O2(g)  <y_axis>  0.1
   Fe(OH)3(a) 0 0

 Magnetite 0 0
 Hematite 0 0
 Greigite 0 0
 Siderite 0 0
END                     

Hope you can help,

Thanks

Jack

[dlparkhurst]

The problem is that Fe(OH)3(a) is not defined in minteq.dat. I found the problem by running a straight PHREEQC calculation.

Add the following before the SOLUTION 1 definition:

Code: [Select]

PHASES
Fe(OH)3(a)
Fe(OH)3 + 3 H+ = Fe+3 + 3 H2O
-log_k 4.891


[jt2020]

Ah I see,

Thank you! I'll give it a go